Apparatuses and methods for controlling a variable speed transmission

ABSTRACT

Apparatuses and methods are disclosed for controlling a variable-speed transmission utilizing a pulley structure including first and second pulley members coupled for free rotation together about a shaft. The second pulley member can be axially movable relative to the first pulley member, and can include a pulley contact surface disposed generally opposite to the first pulley member. A coupling member is provided for communicating with the shaft to rotatably drive the shaft. The coupling member includes a coupling member contact surface disposed for selective frictional engagement by the pulley contact surface. Torque can be selectively coupled and decoupled to a transmission, as well as vary a speed of the transmission.

RELATED APPLICATIONS

This application is a divisional patent application which claims thebenefit of the filing date of U.S. patent application Ser. No.10/751,768, filed Jan. 5, 2004, the disclosure of which is incorporatedherein by reference in its entirety.

TECHNICAL FIELD

The subject matter disclosed herein generally relates to variable-speedtransmissions and, more specifically, to a control apparatuses andmethods that can be implemented with such a transmission to operate asboth a coupling mechanism and a speed-varying mechanism.

BACKGROUND

Many types of transmissions are capable of operating at variable speeds.Typically, a variable-speed transmission includes a means for adjustingspeed in response to control by an operator using a machine comprisingthe transmission. One type of transmission utilizes one or morevariable-pitch pulleys to enable speed variation. As generally known topersons skilled in the art, a variable-pitch pulley typically includestwo plates defining a groove therebetween for carrying a belt driven bya motor. One of the plates is axially movable relative to the other,such as along a central hub, while the other plate remains fixed inposition to a shaft about which the plates of the pulley rotate. Cams orother means are employed to cause the movable plate to move toward oraway from the other plate, such as by changing the tension in the belt,thereby varying the pitch of the pulley (i.e., widening or narrowing itsgroove) and enabling the belt to move away from or toward the shaft(i.e., running the belt at a shallow or deep position within thegroove). The speed of the shaft changes in response to the change inposition of the belt within the groove defined between the plates.Examples of the use of variable-pitch pulleys are disclosed in U.S. Pat.Nos. 4,322,934; 4,653,345; 4,924,988; and 6,186,916; and U.S. PatentApplication Pub. No. US 2002/0183145.

While variable-pitch pulleys often perform well in cooperation withtransmissions for the conventional purpose of varying speed betweenminimum and maximum values, such pulleys are not capable of providing acomplete and/or effective engagement or disengagement of the torquesupplied to the transmission. In one approach disclosed in U.S. Pat. No.4,322,934, a transmission is powered by a motor and includes abelt-driven variable-pitch pulley. The motor is, in a sense,“disengaged” from the transmission by decreasing tension on the beltdriving the variable-pitch pulley to such a degree that the belt can nolonger drive the pulley. This approach can cause the belt to prematurelywear due to slippage on the surfaces of the pulley and the repeatedcycling of the belt between extreme tensioned and relaxed states.Moreover, additional driving components such as extra pulleys and beltsare required so that other operative components driven by the motor,such as blades in the case of a lawnmower, are not affected by theslackening of the variable-pitch pulley's belt.

In other approaches, the function of engagement disengagement hasrequired the use of a separate transmission component dedicated for thatpurpose, such as a cone clutch, dog clutch, ratchet, brake, pressureplate or friction disk assembly, or the like. Moreover, separate controlmechanisms have often been required to enable an operator to controlengagement/disengagement and speed variation. Examples includetransmissions disclosed in U.S. Pat. No. 6,186,916 and U.S. PatentApplication No. US 2002/0183145. In these two references, the pitch of avariable-pitch pulley is changed by rotating a cam device, whilemaintaining tension in the belt driving the pulley. Such transmissionsrequire a separate clutch to effect engagement and disengagement.

In another example, U.S. Pat. No. 4,653,345 likewise discloses atransmission in which a variable-pitch pulley is adjustable by rotatinga cam device. In addition, the transmission of U.S. Pat. No. 4,653,345includes a separate, internal shifting assembly disposed within thetransmission's housing, remotely from the variable-pitch pulley. Theshifting assembly switches the transmission between driving and neutralstates. A control lever is connected both to the rotatable cam deviceand, through a linkage assembly, to the shifting assembly. Rotation ofthe control lever actuates both the cam device and the shiftingassembly. The variable-pitch pulley and the shifting assembly areseparate devices, require a relatively large number of components, andinvolve a degree of complexity and cost unsuitable for many types ofcommercial applications.

It would therefore be advantageous to provide a control apparatuses andmethods for use with a transmission that integrally combines thefunctions of both selective coupling and speed variation, therebyeliminating the number, complexity, and cost of transmission componentsrequired for the transmission.

SUMMARY

According to one embodiment, an apparatus for controlling avariable-speed transmission comprises a pulley structure and a couplingmember. The pulley structure comprises first and second pulley memberscoupled for free rotation together about a common axis. The secondpulley member is axially movable relative to the first pulley member andcomprises a pulley contact surface disposed generally opposite to thefirst pulley member. The coupling member is rotatable about the axis,and comprises a coupling member contact surface disposed for selectivefrictional engagement by the pulley contact surface.

According to another embodiment, an apparatus for controlling avariable-speed transmission comprises a pulley structure and a couplingmember. The pulley structure comprises first and second pulley memberscoupled for free rotation together about an axis. The second pulleymember comprises a pulley contact surface disposed generally opposite tothe first pulley member. The second pulley member is axiallytranslatable relative to the first pulley member between a disengagedposition and an engaged position. While in the engaged position, thesecond pulley member is axially translatable among variable speedpositions. The coupling member is rotatable about the axis, andcomprises a coupling member contact surface generally facing the pulleycontact surface. At the disengaged position, the pulley contact surfaceis axially spaced from the coupling member contact surface. At theengaged position, the pulley contact surface frictionally engages thecoupling member contact surface for enabling the pulley structure torotatably drive the coupling member at variable speeds.

According to yet another embodiment, an apparatus for controlling avariable-speed transmission comprises a shaft, first and second pulleymembers coaxially disposed and freely rotatable about the shaft, and acoupling member communicating with the shaft for driving rotationthereof. The second pulley member is coupled to the first pulley memberfor rotation therewith and axial translation relative thereto along theshaft. The second pulley member comprises a pulley contact surfacedisposed generally opposite to the first pulley member. The couplingmember comprises a coupling member contact surface. The pulley contactsurface is axially movable into frictional engagement with the couplingmember contact surface for transferring torque from the first and secondpulley members, through the coupling member, and to the shaft.

In a method for controlling a variable-speed transmission, at least aportion of a rotating pulley structure is caused to engage a couplingmember to enable the pulley structure to rotatably drive the couplingmember. The pulley structure is adjusted to vary a speed at which thepulley structure drives the coupling member.

It is therefore an object to provide apparatuses and methods forcontrolling a variable speed transmission.

An object having been stated hereinabove, and which is achieved in wholeor in part by the present disclosure, other objects will become evidentas the description proceeds when taken in connection with theaccompanying drawings as best described hereinbelow.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a partially cross-sectional side elevation view of a controlapparatus as disclosed herein, in a neutral or disengaged position;

FIG. 1B is a partially cross-sectional side elevation view of thecontrol apparatus in an engaged, LOW speed position;

FIG. 1C is a partially cross-sectional side elevation view of thecontrol apparatus in an engaged, HIGH speed position; and

FIG. 2 is a schematic view of an example of a drive system in which acontrol apparatus according to the present subject matter can beimplemented.

DETAILED DESCRIPTION

In the following description, control apparatuses are disclosed that canbe employed in conjunction with a transmission. The control apparatusesare structured so as to function as both a coupling/decoupling mechanismand as a speed-varying mechanism. In one aspect, the control apparatusincludes a structural feature or features functioning analogously to aclutch or other type of frictional engagement mechanism, enabling atorque input to be selectively coupled and decoupled from thetransmission. In another aspect, the control apparatus includes astructural feature or features functioning analogously to a“variable-pitch” or “adjustable” pulley, enabling a driving member suchas a belt carried by the pulley structure to be displaced at variablepositions relative to the axis about which the pulley structure rotates.

Referring now to FIG. 1A, a control apparatus for a transmission isillustrated according to an advantageous embodiment and is generallydesignated CA. Control apparatus CA is operatively associated with atransmission, generally designated T, that receives torque from an inputshaft IS. Generally, transmission T includes a main housing H that canenclose suitable internal components, such as gears, shafts and thelike, needed for various functions such as torque transfer, speedreduction, and providing different axes of rotation. It will becomeevident from the following description, however, that the use of controlapparatus CA as disclosed herein eliminates the need for a clutch and/orshifting mechanism within main housing H.

Transmission T can have any configuration suitable for transferringtorque from input shaft IS to any suitable output, such as one or moreoutput shafts (not shown) connected to one or more driven wheels (notshown). For this purpose, input shaft IS in the present embodiment canreceive torque from a suitable prime mover or motor M (FIG. 2), such asan electric motor or an internal combustion engine, through a suitabletorque transferring means. In the advantageous embodiment illustrated inFIG. 1A, input shaft IS can be driven over a range of variable angularspeeds by providing a torque transferring means that includes a uniquelystructured and operative variable-pitch transmission pulley, generallydesignated TP. Transmission pulley TP carries and is driven by asuitable rotatable endless member EM such as a belt. In addition totransmission pulley TP, control apparatus CA can comprise a couplingmember CM secured to input shaft IS. Coupling member CM interacts withtransmission pulley TP in a manner described below.

Accordingly, in advantageous embodiments, transmission T can be avariable-speed transmission, and particularly a continuouslyvariable-speed transmission. In a typical implementation, it isenvisioned that transmission T can operate in conjunction with anysuitable motor-powered machine, including one designed for mobility overa surface such as a self-propelled lawnmower. As appreciated by personsskilled in the art, by manipulating an appropriate control assemblycommunicating with transmission T (e.g., a hand-operated lever andassociated linkage), an operator can control the output speed of acontinuously variable-speed transmission, and thus the speed of one ormore driving wheels if provided, over a continuous or substantiallycontinuous range between a minimum low speed (which can be zero) and amaximum high speed. Generally, for the embodiments disclosed herein, thevariation/adjustment of torque and/or transmission speed can be effectedthrough the axial translation of one or more components of transmissionpulley TP in a manner described below.

Referring now to FIG. 2, a drive system, generally designated DS, isschematically illustrated as an example of an implementation of controlapparatus CA. In drive system DS, endless member EM is wrapped around amotor pulley MP as well as transmission pulley TP. FIG. 2 depicts theoperation of transmission pulley TP as a variable-pitch pulley structureby illustrating endless member EM in two extreme (i.e., shallow anddeep) positions that generally correspond to FIGS. 1A and 1C,respectively. Motor pulley MP rotates about a motor shaft MS thattransfers torque produced by motor M. Through the rotation of endlessmember EM, the torque from motor shaft MS and motor pulley MP istransferred to transmission pulley TP. A speed-varying actuation devicecan be provided to control and adjust tension in endless member EM. Byway of example, an idler or tensioning pulley IP is employed not only tomaintain tension in endless member EM but also to deliberately adjustthis tension in order to vary the pitch of transmission pulley TP, asdescribed below. For this purpose, idler pulley IP is movable along alinear or non-linear path generally represented by arrow A. By way ofadditional example, motor M and transmission T could be mounted to amower deck (not shown) of a lawnmower, in which case motor shaft MS ofmotor M could also rotatably drive a suitable cutting element (notshown) such as a blade or blades disposed within an interior of themower deck. With motor M also transferring power to the driving wheel orwheels of the lawnmower through transmission T, the lawnmower could beself-propelled in response to control by the operator.

Referring back to FIG. 1A, in advantageous embodiments, transmissionpulley TP is structured as a variable-pitch pulley as noted above.Transmission pulley TP comprises two flanges or halves, illustrated as afirst pulley member PM₁ and a second pulley member PM₂. To enable thepitch or distance between first and second pulley members PM₁ and PM₂ tobe varied, at least one of first and second pulley members PM₁ and PM₂is axially translatable along input shaft IS relative to the other. Inthe present embodiment, first pulley member PM₁ is axially stationaryand second pulley member PM₂ is axially movable. Unlike conventionalvariable-pitch pulleys that are directly attached to a shaft, neitherfirst pulley member PM₁ nor second pulley member PM₂ in the presentembodiment is directly attached to input shaft IS. Instead, both firstand second pulley members PM₁ and PM₂ of transmission pulley TP arefreely rotatable about input shaft IS. First pulley member PM₁ ismechanically referenced to second pulley member PM₂ by any suitablemeans that permits first pulley member PM₁ to rotate with second pulleymember PM₂ while, at the same time, enabling the axial adjustment offirst pulley member PM₁ relative to second pulley member PM₂. Forinstance, first pulley member PM₁ can include a central bore 12 coaxialto, but annularly spaced from, input shaft IS, and a splined pulley hubPH that at least partially defines bore 12. Second pulley member PM₂ caninclude a central bore 14 having complementary splines (not shown) thatslidingly engage pulley hub PH. Alternatively, pulley hub PH could beintegrated or otherwise associated with second pulley member PM₂. Firstpulley member PM₁ and pulley hub PH rotate freely about input shaft ISby any suitable means such as one or more bearings 16A and 16B (e.g.,roller bearings). One or more of bearings 16A and 16B can additionallyfunction as thrust bearings to retain first pulley member PM₁ in astationary axial position, or additional bearings or other retainingmeans can be provided for this purpose. As an additional example, inputshaft IS can have a reduction in diameter to form an annular shoulder orstep 18 against which bearing 16A abuts.

As in the case of conventional variable-pitch pulleys, the pitch oftransmission pulley TP can be adjusted to vary the radius of rotation ofendless member EM carried thereby. As shown in FIG. 1A, thecross-section of endless member EM, and respective inside surfaces 20Aand 20B of first and second pulley members PM₁ and PM₂, can becomplementarily tapered to facilitate movement of endless member EMtoward and away from input shaft IS. For instance, widening the distancebetween first and second pulley members PM₁ and PM₂ causes the endlessmember EM to make frictional contact with first and second pulleymembers PM₁ and PM₂ at a location radially closer to input shaft IS withwhich transmission pulley TP rotates. In FIGS. 1B and 1C, for example,arrow B generally represents radially inward displacement of endlessmember EM toward input shaft IS, and arrow C generally represents axialtranslation of second pulley member PM₂ away from first pulley memberPM₁.

In advantageous embodiments, endless member EM can be actuated in asuitable manner to vary the pitch of transmission pulley TP by causingaxial translation of second pulley member PM₂ relative to first pulleymember PM₁. For instance, the movement of endless member EM toward inputshaft IS forces second pulley member PM₂ to move away from first pulleymember PM₁ through contact between endless member EM and inside surfaces14A and 14B. An example of actuating endless member EM is illustrated inFIG. 2, in which idler pulley IP can be moved along a path such as arrowA to increase tension in endless member EM. Assuming a given frequency wat which endless member EM is rotating under the driving force of motorM, the reduction in the radius r at which endless member EM turnsrelative to input shaft IS results in an increased angular velocity α atwhich input shaft IS is driven by endless member EM, according to therelation α=w/r. It will be noted that for many implementations ofvariable-speed transmissions, endless member EM rotates at a constantfrequency w under normal operating conditions, due to the output speedof motor M being constant (e.g., 3100 rpm) under normal operatingconditions for the purpose of operational-related optimization.

Although not specifically shown in the drawings, in some embodiments,motor pulley MP (FIG. 2) could also be a variable-pitch pulley. In thiscase, however, the pitch of motor pulley MP would vary inversely to thatof transmission pulley TP to maintain tension in endless member EM andthus maintain the transfer of motor-produced torque to transmissionpulley TP. For instance, the pitch of motor pulley MP would increasewhile the pitch of transmission pulley TP would decrease. In addition,pitch of motor pulley MP would vary on a different scale or proportionas compared with transmission pulley TP to enable the variance in thepitch of transmission pulley TP to adjust the speed ratio as betweenmotor shaft MS and input shaft IS.

Referring again to FIG. 1A, additional features of control apparatus CAwill now be described. Unlike conventional variable-pitch pulleys,transmission pulley TP functions not only to vary speed but also tocompletely couple/decouple motor-produced torque to/from input shaft IS.Accordingly, transmission pulley TP can be characterized as serving notonly as a speed-varying mechanism, but also as a clutch or couplingmechanism for transmission T. For this purpose, the axially movablecomponent of transmission pulley TP, which is second pulley member PM₂in the illustrated embodiment, includes an outside surface that servesas a frictional pulley contact surface 22. The surface of couplingmember CM facing second pulley member PM₂ serves as a frictionalcoupling member contact surface 24. By this configuration, increasingthe pitch of transmission pulley TP eventually causes pulley contactsurface 22 to come into frictional contact with, and thus engage,coupling member contact surface 24. Due to the resulting pressureimparted to coupling member contact surface 24 by pulley contact surface22, rotation of transmission pulley TP forcibly can cause rotation ofcoupling member CM. Coupling member CM can be secured to input shaft ISfor rotation therewith by any suitable means, such as mated splines 26,key and keyway, set screw and threaded bore, press fitting, or the like.Thus, frictional contact between pulley contact surface 22 and couplingmember contact surface 24 enables the torque supplied to transmissionpulley TP to be transferred to coupling member CM and input shaft IS,thereby driving the internal components of transmission T associatedwith input shaft IS.

As further shown in FIG. 1A, pulley contact surface 22 and couplingmember contact surface 24 can have complementary profiles. Stateddifferently, at least a portion each of pulley contact surface 22 andcoupling member contact surface 24 has a contour comprising one or morecurved or linear sections. For example, in the illustrated embodiment,at least a portion each of pulley contact surface 22 and coupling membersurface 24 is angled relative to the axis about which input shaft ISrotates. This profiled configuration is analogous to a cone clutchdesign which, in conventional implementations, is known for providing asmooth transition between engagement and disengagement. In the exampleillustrated in FIG. 1A, pulley contact surface 22 or at least a portionthereof is convex, and coupling member contact surface 24 or at least aportion thereof is concave. In alternative embodiments, however, pulleycontact surface 22 can include the concavity and coupling member contactsurface 24 can include the complementary convexity. Moreover, theembodiments herein are not limited to profiled frictional contactsurfaces. That is, pulley contact surface 22 and coupling member contactsurface 24 could each be flat. Furthermore, pulley contact surface 22and coupling member contact surface 24 could each present complementaryor mating features that do not rely solely on friction for engagement,such as teeth, pawls, dogs, or the like.

As additionally shown in FIG. 1A, control apparatus CA can include abiasing member for biasing second pulley member PM₂ toward first pulleymember PM₁, and hence biasing control apparatus CA toward slower speedsand even complete disengagement if insufficient effort is made toactuate endless member EM so as to keep transmission pulley TP open. Inthe illustrated embodiment, the biasing member comprises a pulley spring32 interconnected between first and second pulley members PM₁ and PM₂and mounted around a bolt or other spring mounting member 34 extendingbetween first and second pulley members PM₁ and PM₂. Spring mountingmember 34 can be secured to both first and second pulley members PM₁ andPM₂, or secured to one while merely retained in a bore of the other.Particularly when control apparatus CA and transmission T areincorporated in a self-propelled machine, pulley spring 32 can beemployed as a safety feature for increasing the effort required by anoperator to actuate control apparatus CA (such as by actuating idlerpulley IP shown in FIG. 2) to engage transmission T and subsequentlyincrease speed. Other, alternative techniques for providing a biasingmember could be provided for the function just described, now known orlater developed, and as such fall within the scope of the embodimentsdisclosed herein.

Continuing with FIG. 1A, control apparatus CA can include a secondbiasing member for biasing coupling member CM toward second pulleymember PM₂, and hence biasing control apparatus CA toward slower speeds.In the illustrated embodiment, this second biasing member comprises acoupling member spring 42 disposed about input shaft IS. Coupling memberspring 42 is interposed between, and in contact with, an outside surface44 of coupling member CM opposite to coupling member contact surface 24and a suitable retaining component 46 such as a washer. Retainingcomponent 46 abuts a nut 48 threaded on input shaft IS. Particularlywhen control apparatus CA and transmission T are incorporated in aself-propelled machine, coupling member spring 42 can be employed as asafety feature for increasing the effort required by an operator toactuate control apparatus CA to increase speed. Moreover, in a casewhere transmission T is provided in a mobile machine, coupling memberspring 42 can be employed to provide resistance against abruptacceleration so as to prevent the machine from jumping forwardimmediately upon engagement of pulley contact surface 22 with couplingmember contact surface 24.

In the embodiment illustrated in FIG. 1A, transmission pulley TP isgenerally interposed between main housing H of transmission T andcoupling member CM. However, as can be appreciated by persons skilled inthe art, the ability of control apparatus CA to operate outside mainhousing H permits the components of control apparatus CA to be orienteddifferently if desired. For instance, the illustrated arrangement ofcontrol apparatus CA could be inverted relative to input shaft IS suchthat coupling member CM is interposed between transmission pulley TP andmain housing H, with transmission pulley TP being farthest from mainhousing H. In such a case, coupling member spring 42 and retainingcomponent 46 could be suitably secured to input shaft IS betweencoupling member CM and main housing H, or coupling member spring 42could be retained directly by main housing H. Such requiredmodifications or alterations to the exemplary embodiment illustrated anddescribed herein are readily apparent to persons skilled in the artwithout undue experimentation, and fall within the scope of theembodiments disclosed.

Referring now to FIGS. 1A, 1B and 1C, the operation of control apparatusCA will now be described. FIGS. 1A, 1B and 1C respectively illustratethree primary states attainable through actuation of control apparatusCA. As noted above, the actuation of control apparatus CA among thesestates can be effected by any suitable means. In the example given inFIG. 2, idler pulley IP is provided to adjust the position and/ortension of endless member EM. Idler pulley IP can be actuated by anoperator of a machine in which control apparatus CA operates, such as alawnmower. For example, idler pulley IP can be actuated throughmanipulation by the operator of a suitable handle or handle-mountedcontrol component (e.g., knob, lever, or the like, not shown) that canbe linked to idler pulley IP directly or through a mechanical,electromechanical, electronic or wireless linkage. It can be appreciatedthat, because control apparatus CA is capable of bothcoupling/decoupling transmission T and varying the speed of transmissionT, only a single operator-manipulatable control component would beneeded for actuating idler pulley IP or an equivalent device and henceactuating control apparatus CA. By contrast, many conventionaltransmission-related assemblies require separate control means forcoupling/decoupling transmission T and varying the speed of transmissionT.

FIG. 1A illustrates a disengaged, OFF or neutral state. In thedisengaged state, a gap (axial distance) exists between pulley contactsurface 22 and coupling member contact surface 24. Thus, transmissionpulley TP can rotate freely without contacting coupling member CM, andthe path of power transfer between motor M (FIG. 2) and transmission Tis decoupled. In the disengaged state, transmission pulley TP can befully “closedl”, the pitch between first and second pulley members PM₁and PM₂ can be at a minimum, and the radius of rotation of endlessmember EM as it is carried by first and second pulley members PM₁ andPM₂ can be at a maximum. In addition, the speed of transmission T iszero because it is not being actively driven. Alternatively, if controlapparatus CA has been actuated from an engaged state to the disengagedstate, the speed of transmission T can slow down to zero because it isno longer being actively driven. Pulley spring 32 assists in maintainingclosure of transmission pulley TP while in the disengaged state.

FIG. 1B illustrates an engaged or ON state, as well as a LOW speedstate. In comparison to FIG. 1A, endless member EM has moved radiallyinwardly toward input shaft IS, and second pulley member PM₂ has movedaxially away from first pulley member PM₁. These movements can beeffected, for example, by actuating idler pulley IP (FIG. 2) to deflectand/or increase tension in endless member EM. In the engaged state, thegap shown in FIG. 1A no longer exists, as pulley contact surface 22 hasbeen brought into frictional engagement with coupling member contactsurface 24. Thus, the rotation of transmission pulley TP (as driven byendless member EM) rotates coupling member CM and thus input shaft IS,thereby coupling the path of power transfer between motor M (FIG. 2) andtransmission T. At the point of engagement, transmission pulley TP ispartially “open”, the pitch between first and second pulley members PM₁and PM₂ has increased, and the radius of rotation of endless member EMhas decreased. Moreover, at the point of engagement, the radius ofrotation of endless member EM has the largest value possible whilesecond pulley member PM₂ is in contact with coupling member CM. This isbecause for any larger value for the radius of rotation, second pulleymember PM₂ will be closer to first pulley member PM₁ and hence will notcontact coupling member CM, as shown for example in FIG. 1A. Thus, atthe point of engagement, the resulting speed at which transmission T isactively driven by motor M (FIG. 2) is at a minimum (i.e., the LOW speedstate).

FIG. 1C illustrates the engaged or ON state, but at a HIGH speed state.In comparison to FIG. 1B, endless member EM has moved further radiallyinwardly toward input shaft IS, and second pulley member PM₂ has movedfurther axially away from first pulley member PM₁. These movements canbe effected, for example, by actuating idler pulley IP (FIG. 2) by agreater amount to deflect and/or increase tension in endless member EM.As control apparatus CA is actuated into the HIGH speed state from theLOW speed state (FIG. 1B) and intermediate states, coupling memberspring 42 ensures that the pressure applied to coupling member contactsurface 24 by pulley contact surface 22 increases, thereby maintaininggood frictional engagement and suppressing slippage between pulleycontact surface 22 and coupling member contact surface 24 at thesehigher speeds. Moreover, as noted above, coupling member spring 42 canprevent an abrupt transition to a high speed soon after the time ofengagement. At the HIGH speed state, transmission pulley TP is fully“open”, the pitch between first and second pulley members PM₁ and PM₂has increased to a maximum, the radius of rotation of endless member EMis at a minimum, and the resulting speed at which transmission T isdriven by motor M (FIG. 2) is at a maximum.

In the operation of control apparatus CA, it can be appreciated that apotentially infinite number of intermediate engaged states, and thusrotational speeds, are available between the LOW speed state illustratedin FIG. 1B and the HIGH speed state illustrated in FIG. 1C. Theseintermediate conditions are attainable through manipulation of theactuating device chosen for cooperation with control apparatus CA, suchas idler pulley IP shown in FIG. 2 and any associated linkages, handle,or the like provided for the specific embodiment.

As indicated above, control apparatus CA can be utilized in conjunctionwith any motor-powered machine that utilizes a transmission TI. Inparticular, control apparatus CA is useful when implemented inself-propelled machines, of either the walk-behind or riding type, suchas lawnmowers, snow blowers, leaf blowers, yard vacuums, tillers,edgers, seeders, trimmers, aerators, fertilizers, palette trucks,graders, vehicles for transportation, pavement and constructionmachines, and the like. Moreover, control apparatus CA can be utilizedin conjunction with any non-mobile machine or tool that includes arotating component requiring speed adjustment and an ON/OFF,clutching-type capability.

It will be understood that various details of the presently disclosedsubject matter may be changed without departing from the scope of thesubject matter. Furthermore, the foregoing description is for thepurpose of illustration only, and not for the purpose of limitation.

1. A method for controlling a variable-speed transmission, comprising:(a) causing at least a portion of a rotating pulley structure to travelbetween a disengaged position to an engaged position to engage acoupling member to enable the pulley structure to rotatably drive thecoupling member; and (b) adjusting the pulley structure to vary a speedat which the pulley structure drives the coupling member.
 2. The methodaccording to claim 1 wherein causing the pulley structure portion toengage the coupling member comprises moving the pulley structure portioninto frictional engagement with the coupling member.
 3. The methodaccording to claim 1 wherein the pulley structure comprises first andsecond pulley members, and causing the pulley structure portion totravel comprises axially moving the second pulley member relative to thefirst pulley member along an axis about which the first and secondpulley members rotate.
 4. The method according to claim 3 whereinadjusting the pulley structure to vary the speed comprises, aftercausing the pulley structure portion to engage the coupling member,further axially moving the second pulley member relative to the firstpulley member along the axis.
 5. The method according to claim 1 whereinthe pulley structure comprises first and second pulley members, andadjusting the pulley structure to vary the speed comprises axiallymoving the second pulley member relative to the first pulley memberalong an axis about which the first and second pulley members rotate. 6.The method according to claim 1 comprising driving the pulley structurewith an endless member in contact therewith, wherein the endless memberrotates at a radius relative to an axis about which the pulley structurerotates.
 7. The method according to claim 6 wherein causing the pulleystructure portion to travel comprises moving the endless member inwardlytoward the axis to decrease the radius of rotation of the endlessmember.
 8. The method according to claim 7 wherein moving the endlessmember inwardly comprises actuating a speed-varying actuation device. 9.The method according to claim 8 wherein actuating a speed-varyingactuation device comprises moving an adjustably movable idler pulleycontacting the endless member.
 10. The method according to claim 7wherein adjusting the pulley structure to vary the speed comprises,after causing the pulley structure portion to engage the couplingmember, moving the endless member inwardly toward the axis to furtherdecrease the radius of rotation.
 11. The method according to claim 6wherein adjusting the pulley structure to vary the speed comprisesmoving the endless member inwardly toward the axis to decrease theradius of rotation of the endless member.
 12. The method according toclaim 11 wherein moving the endless member inwardly comprises actuatinga speed-varying actuation device.
 13. The method according to claim 12wherein actuating a speed-varying actuation device comprises moving anadjustably movable idler pulley contacting the endless member.
 14. Themethod according to claim 1 wherein driving the coupling membercomprises driving a shaft attached to the coupling member.
 15. Themethod according to claim 1 comprising providing a biasing force actingagainst engagement by the pulley structure portion with the couplingmember to increase the effort required for causing engagement.
 16. Themethod according to claim 1 comprising providing a biasing force actingagainst adjustment of the pulley structure to increase the effortrequired for increasing the speed.